Conventional commutating filters, when operated at a proper commutating frequency, pass not only the fundamental frequency but also the d.c. component thereof and all harmonics thereof. It is often desirable that the filter reject the d.c. component and sometimes desirable that the filter reject even harmonics of a fundamental frequency presented thereto. This desirability lacking in conventional commutating filters is offset by the fact that, relative to conventional filters, a commutating filter has the desirable characteristics of being a very high Q filter, preserving the input waveform, being easily tuned and being of compact size in that it requires no chokes.